Device for the quantitative analysis of debris

ABSTRACT

A device for the quantitative analysis of debris preferably produced while drilling, comprising means for the progressive collection of debris, means for the progressive weighing of collected debris, means for unloading the same preferably in a discharge channel, and a support structure for the device wherein said means for the collection of the debris comprise a collection tray which is capable of performing two types of movement: a rotation movement around an axis which allows alternate loading and unloading of debris and a backward movement which is simultaneous with the rotation movement, thereby allowing for a decisive reduction in the overall vertical dimension of the structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the priority filing date ofItalian patent application n° MI2010A000736 filed on Apr. 29, 2010 inthe name of Geolog SpA.

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

STATEMENT REGARDING COPYRIGHTED MATERIAL

Portions of the disclosure of this patent document contain material thatis subject to copyright protection. The copyright owner has no objectionto the facsimile reproduction by anyone of the patent document or thepatent disclosure as it appears in the Patent and Trademark Office fileor records, but otherwise reserves all copyright rights whatsoever.

BACKGROUND Field of the Invention

The present invention relates to a device for the quantitative analysisof debris produced while drilling a well. Said device is of thestand-alone type, i.e. able to function in an independent manner fromother devices such as a data acquisition unit.

At the current state of art, the drilling of soil is commonly performedwith a rotary system, i.e. through the use of a rotating drill bitscrewed to the end of a progressive series of drill rods. Recently, anew technique has been introduced that allows wells to be formed in away that does not follow a trajectory perpendicular to the drilledsurface, but instead a deviated trajectory. Said wells develop in excessof 35,000 feet in depth in an almost horizontal manner through theprogressive curving of the rods.

When the drilling reaches such depths, the augers are subjected totorsional torques far greater than those following a verticaltrajectory. In these cases, it is of capital importance to adjust thework parameters of the drilling in real time, such as the speed ofrotation and penetration of the auger, the dynamic of circulation of thefluids and their rheological properties. In particular, it is of vitalimportance to check the geometry of the well excavated and the behaviourof the rock walls that define the internal surface of the well.

In order to be able to contrast the thrust force of the formationstraversed and the fluids contained therein, a drilling fluid is fed intothe well to contrast the pressure of the hydrocarbons. Said fluid alsoserves to transport debris produced during drilling outside of the well.The elimination of the debris is fundamental because an accumulation ofdebris in the gap between the auger and the walls of the well causes anincrease in the resistance torque, creating a risk of blockage andbreakage of the auger itself.

The variation in volume of the well during drilling can be expressed bythe following relation:

$\frac{{V(t)}}{t} = {{{{\overset{\rightarrow}{S}\left( {\overset{\rightarrow}{x},t} \right)} \times {\; {\overset{\overset{\rightarrow}{.}}{x}(t)}}{t}} + {Q\left( {{\overset{\rightarrow}{x}}^{\prime},{t + \tau_{1}}} \right)}} = {v\left( {t + \tau_{2}} \right)}}$

where V(t) represents the volume of the well in the instant t, S thearea of the section of the well at the instant t and the depth x and Qis a source term.

It is clear therefore that the variation of the volume of the well inthe unit of time (dV(t)/dt) is equal to the sum of a source term Q andof the product of the area S of the section of the well at the samedepth and at the same instant and the advancement dx dt of the auger inthe infinitesimal interval of time dt.

At the mouth of the well, it is possible to measure the volume v of thedebris transported by the drilling fluid, with a certain delay τ₂ inrelation to the instant t. This delay is due to the speed of circulationof the fluid which has to transport the debris as far as the mouth ofthe well and to its rheological properties.

It is clear that the source term Q will be equal to the differencebetween the variation in the volume of the well and the volume of thedebris transported by the drilling fluid; said source term Q being ableto supply fundamental information for monitoring the drilling. In fact,when Q is negative, it means that a dangerous accumulation of debris inthe well is probably occurring and there is a risk of the augerbreaking. If, instead, Q is positive, there has probably been alandslide inside the well and therefore the walls are unstable.

This type of monitoring or quantitative analysis of the debris isparticularly important in deviated drilling because the well is verylong and the problems of stability and cleanliness of the hole areaccentuated.

The quantitative analysis of the debris, i.e. measurement of the weightof the debris and therefore of its volume, is carried out by means ofspecific machinery located at the well mouths. When the drilling fluidwhich carries the debris reaches the surface, said fluid traversesspecial vibrating screens which separate the solid debris from theliquid. Said debris is then conveyed onto apparatuses for weighing.

One of the first solutions provided by the market was that described indocument EP0995009 in the name of Geoservices. Said device provides forthe use of means for collecting the debris and means for measuring theirweight in a continuous manner. Said means for collecting debris comprisea tray rotating around an axis, means for tilting said tray so as toempty it and means of driving said means for tilting the tray. Connectedto said means for tilting the tray is a measuring cell able to measurethe bending moment of the tray in relation to its axis of rotation, itthen being possible to calculate the weight of the debris based on thevalue measured from said bending moment.

The measured weight of the debris based on the bending moment, as occursin the device described in EP0995009, is, however, imprecise due to theuncertainty of the location of the centre of mass of the debrisdistributed on the tray in relation to the axis of rotation of the same.

Because the surface of the tray must have a width equal at least tostandard vibrating screens and a certain volume is required for the trayto perform its rotation, the dimensions of the entire structure of thedevice (described in the document in the name of Geoservices) arenecessarily considerable. Consequently, in many operating situations inwhich there is a real lack of space, it is not possible to use aninstrument such as that described in EP0995009; thereby abandoning animportant supply of information derived from quantitative analysis ofdrilling debris.

New ideas were introduced into the market, the most important of whichis that described in U.S. Pat. No. 1,366,349 in the name of GeologS.p.A. This patent relates to a device for the quantitative analysis ofdebris provided with means for collecting debris comprising a conveyorbelt wound in a manner of a track on at least two rollers and means formeasuring the weight of the debris comprising at least fourextensometric cells.

Said extensometric cells are arranged preferably at the four corners ofa base upon which the support structure of the device is placed in orderto perform a direct measurement of the weight force exerted on theconveyor belt.

In this way, some of the limitations of the Geoservices device areovercome because the systematic imprecision, due to the uncertainty ofthe location of the centre of mass of debris distributed on the tray inrelation to the axis of rotation, is eliminated.

Despite the advantages of the device of U.S. Pat. No. 1,366,349 in thename of Geolog S.p.A over other devices for weighing debris bytraditional systems, there are still some elements to be improved, inparticular, the considerable bulk and, therefore, flexibility of use inall working environments including the most critical and restrictiveconditions.

Moreover, devices for the quantitative analysis of debris present in theart cannot be used in stand-alone form, i.e. independently from otherservices. Instead, they must be supported by a data acquisition unit.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to provide a device for thequantitative analysis of debris produced in the drilling of a well,which is capable of operating under restrictive conditions as in thecase of the new generations of drilling plants characterised byextremely reduced and complex geometries and distribution of space,e.g., deep sea drilling plants.

The abovementioned object of the present invention is achieved byreducing the vertical overall dimension of the equipment, whilemaintaining all functions of the system.

Another object of this device is to be able to install it in a mannertotally independent manner from other services, i.e. in stand-aloneform, by limiting the dimensions of the equipment and control system sothey are suitable for normal office space.

These and other objects are achieved by a device according to thepresent invention for the quantitative analysis of debris, preferablyproduced while drilling, comprising means for the progressive collectionof debris, means for the progressive weighing of collected debris, meansfor the periodic unloading of the debris, and a support structure forthe device, characterised in that:

said means for the collection of debris comprise a collection traycapable of performing two types of movement: a rotation movement aroundan axis which allows alternate loading and unloading of debris and abackward movement which, due to simultaneous movement with the rotationmovement, permits a decisive reduction in the overall vertical dimensionof the structure. Because the backward movement and rotation movementare simultaneous, the tray level is lowered during the loading phase, infact, to a height of approximately 15 cm from the walking surface.

Although this is a complex movement, this technical solution reduces toa minimum the number of moving parts (joints, hinges, bearings), therebyensuring simultaneous protection against the entry of fluids (slurry)that could cause friction and abrasions.

Said means for the weighing of the debris comprise at least four sensingelements arranged in such a way as to take a direct measurement of theweight force exerted on the surface of the plate; the plate is made froma steel sheet which varies from 2 to 3 mm in thickness, completelyunrestrained from the rest of the structure, dimensioned and resting onthe four sensing elements in such a way as to guarantee the totalabsence of parasite twisting moments. The measurement therefore takesplace in a direct and homogeneous manner under the surface of the plate,nor is it influenced by external inertias or vibrations, thereforeguaranteeing an electrical signal free from noise.

BRIEF DESCRIPTION OF THE DRAWINGS

Said means for the unloading of the debris comprise at least oneassembly for actuation of said collection plate. These and otheradvantageous features of the present invention will be made clearer onreading the following detailed description of a preferred embodiment,given by way of a non-limiting example,

FIG. 1 shows schematically a drilling plant wherein the position of thedevice for the quantitative analysis of the debris according to thepresent invention is highlighted;

FIG. 2 is a schematic front view of the device for quantitative analysisof debris;

FIG. 3 is a side view (from the side of the box which houses thepneumatic part) of the device for quantitative analysis of debris ofFIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows schematically a drilling plant 1, wherein the device forthe quantitative analysis of the debris 2 according to the presentinvention can be positioned. The drilling fluid 3 follows the followingpath (indicated in the drawing with arrows): the drilling fluid 3 flowsin the hollow interior of the drilling column 4, and exits from the tool5. The drilling fluid 3 draws the debris of the rock as far as thesurface, after having risen up in the annular space existing between thedrilling column 4 and the walls of the well. Having reached the surface,the drilling fluid 3 traverses the vibrating screens 6, consisting ingeneral of a series of vibrating sieves aimed at the separation of thedrilling fluid from the solid debris. The debris is collected by thedevice for the quantitative analysis 2 according to the presentinvention.

Referring to FIGS. 2 and 3 the device for the quantitative analysis ofdebris of the present invention comprises:

a collection tray, preferably in steel (7),

a forks surface (8).

four load cells (9 a, 9 b, 9 c, 9 d),

a rotating shaft (10),

a box which houses the pneumatic part (11),

a box which houses the electronic part (12).

The tray (7) is advantageously dimensioned in such a way that its lengthcoincides substantially with the transverse dimensions of the dischargechannel of the vibrating screens, from which the flow of debris exitscontinuously, while its width allows for the accumulation of a quantityof debris sufficient for obtaining weight measurements that can beinterpreted. The tray is preferably made with AISI 304 stainless steel,which does not deteriorate as a result of chemical attack produced bysubstances dissolved in residual drilling fluid and by the abrasiveaction of the debris itself. The tray has rear discharge ports(intermittent millings) which allows liquid to seep out of the slurry,retaining the solid.

Said tray (7) is provided, moreover, with two lateral fins (13 a) and(13 b) which serve in fact to retain the debris laterally, preventingleakage thereof. The position of the tray when collecting slurry isslightly slanted in such a way as to drain the liquid part not involvedin the measurement. The slant of said tray can be regulated.

Referring in particular to FIG. 3, the actuation assembly whichgenerates the movement of the tray (7) comprises:

a pneumatic piston (14),

a spherical joint (15),

a connecting rod (16) connected to the spherical joint integral by meansof a through pin with a rotation shaft (17).

The movement of the tray (7) is essentially generated by the compressedair piston (14), which pushes or pulls the connecting rod (16) via thespherical joint (15), according to whether it is loaded or unloaded.This piston (14) is actuated by a solenoid valve Eex-i coupled to adistribution manifold, which by releasing pressurised air at the twoinlets of the pneumatic piston (14) determines the actuation of thepiston, and therefore the movement of the tray.

The excitation of the solenoid valve is determined by the stand-alonecontrol system which allows the following parameters to be changed:loading time, unloading time, weight limit.

The tray is attached to the load cells by means of vibration damperswhose function is to insulate against external vibrations and compensatepossible thermal expansions.

The four cells are in turn attached to a forks surface (8), integral yetmisaligned in relation to the rotating shaft (10).

The device for quantitative analysis of debris according to the presentinvention is also equipped with a hydraulic circuit for supplyingpressurised water, not shown in the drawings, which feeds the nozzles(18) for washing the tray. Said nozzles (18) are placed on a horizontalpipe with a length equal to that of the tray, said pipe being attachedby means of a system having an adjustable slant.

The important function of said nozzles (18) will be made clearer byreading the rest of the description.

The system at the two lateral ends terminates with two distinct boxesintegral with the whole structure: one of said boxes (11) houses thepneumatic part including the solenoid valve, while the other one (12)contains the electronic part.

The box which houses the pneumatic part (11), hereinafter referred to,for simplicity, as pneumatic box, is provided with externalinlets/outlets for the air and water. The box which houses theelectronic part (12), hereinafter referred to, for simplicity, aselectronic box, is designed in such a way that passage via cable glandsis possible both of the cables for the transmission of the electricalsignal and of the cable for supplying the solenoid valve.

The pneumatic box (11) is provided with three pushbuttons which can beactuated by the external operator and are positioned on the closuredoor.

Said pushbuttons are: an actuation pushbutton, a pushbutton for stoppingworking, and an emergency pushbutton for the instantaneous switching-offof the device.

It is also possible to open the pneumatic box and switch the function ofthe solenoid valve from automatic (normal working condition) to manual.

The manual operating mode (via a screw able to perform a 90° rotation)allows said device to be directly managed, making it possible tosimulate movement of the tray by pressing the start and stop pushbuttonsto perform tests (for faults and/or leaks).

On the other hand, the automatic mode provides for the setting of workparameters via a workstation in a remote position (stand-alone system)as will be explained in greater detail below.

The device for the quantitative analysis of debris produced whiledrilling according to the present invention is designed to incrementallymeasure the weight of the debris or of the ratio between the variationof the weight and the interval of time in which said variation ismeasured. The increment of time of collection or the maximum value ofthe increment of the weight is pre-selected by the user on a case bycase basis. Once the solid phase has been separated from the liquidphase of the material which has exited the mouth of the well, thevibrating screens discharge said solid phase (i.e. the debris) directlyonto the collection surface of the tray (7).

Said tray, during the phase of collection, is immobile in a horizontalposition, with a slight slant upwards, while the four extensometriccells generate a voltage signal correlated to the weight of the debriswhich is progressively collected. Once this weight reaches the maximumlimit set, or the interval of time set has passed, the unloading phasetakes place. In this phase, the pneumatic piston (14) is actuatedautomatically and rotates the shaft (10) which, in turn, generates thebackward and rotation movements of the forks surface (8) which isintegral with the four load cells and the relative tray above. The timein which the tray is maintained in a vertical position, i.e. in positionof unloading, is predetermined.

During the phase of unloading, the nozzles (18) spray pressurised waterdownwards, in the rear part of the tray (7). Said water facilitates thedetachment and sliding of any residue. The elimination of the residue isof considerable importance in that the mass of said residue wouldcontinue to condition the weight signal during the subsequent phase ofcollection. The unloading phase foresees a span of time such as to allowadequate washing of the tray. Said span of time, which is selected bythe operator, depends essentially on the quality of the debriscollected.

The work parameters of the device for the quantitative analysis ofdebris are selected by the user via a workstation in a remote location,which also receives the signal coming from the extensometric cells. Saidworkstation is provided with dedicated software for the acquisition,processing and storage in memory of the signals coming from the devicefor the quantitative analysis of debris. Said software also allows forthe visualisation of the cumulative volume of debris as a function oftime, the cumulative volume of debris as a function of depth and thetheoretical profile of the well excavated.

A further advantage of this embodiment, moreover, is that of allowingfor the maintenance or replacement of the extensometric cells solely byremoval of the tray, an operation which can be performed with extremerapidity and ease and which does not entail the movement of largeweights.

Obviously all the known elements described above and used in the presentdevice can be replaced by technically equivalent elements, withoutaltering the functional principles of said device, as claimed herein.

The materials with which the single components are made are known in theart and are suitable, or certified, for operating in highly aggressivesite conditions. Any variations in the materials of the components donot alter in any way what is described and claimed herein.

1. A device for the quantitative analysis of debris preferably producedwhile drilling, comprised of means for the progressive collection ofdebris which comprise at least one collection tray, means for moving theat least one collection tray, means for the progressive weighing of thedebris collected, means for unloading the same, preferably in adischarge channel, and a structure for support of the device, whereinsaid means for moving the at least one collection tray comprise at leastone rotating body, the at least one collection tray being restrained byknown means to the at least one rotating body to perform, as a result ofthe rotation of said rotating body, a movement composed by a rotationand a simultaneous translation resulting from an offset between theplain of the collection tray and the axis of rotation of said rotatingbody, in order to allow said tray to make two simultaneous movements,such as a rotation for loading and unloading and a translation.
 2. Thedevice for the quantitative analysis of debris preferably produced whiledrilling according to claim 1, wherein the simultaneity of said rotarymovement and said translational movement enables the height of the atleast one collection tray to be located preferably to about 15 cm fromthe support surface.
 3. The device for the quantitative analysis ofdebris preferably produced while drilling according to claim 1, whereinsaid means for weighing the debris comprise at least four sensingelements positioned in such a way as to take a direct measurement of theweight force.
 4. The device for the quantitative analysis of debrispreferably produced while drilling according to claim 1, wherein the atleast one rotating body is a shaft.
 5. The device for the quantitativeanalysis of debris preferably produced while drilling according to claim1, wherein said means for moving the at least one collection traycomprise at least one assembly for pneumatic actuation of said rotatingbody.
 6. The device for the quantitative analysis of debris preferablyproduced while drilling according to claim 1, wherein the at least onecollection tray is restrained to that rotating body by means of at leastone forks surface.
 7. The device for the quantitative analysis of debrispreferably produced while drilling according to claim 6, wherein saidforks surface is integral yet misaligned in relation to said rotatingbody.
 8. The device for the quantitative analysis of debris preferablyproduced while drilling according to claim 3, wherein said at least foursensing elements are four load cells and are attached to said forkssurface.
 9. The device for the quantitative analysis of debrispreferably produced while drilling according to claim 5, wherein saidassembly for pneumatic actuation comprehends at least one pneumaticpiston, at least one spherical joint, and at least one rod.
 10. Thedevice for the quantitative analysis of debris preferably produced whiledrilling according to claim 9, wherein the actuation of said pneumaticpiston causes a rotation of said rotating body pushing or pulling the atleast one rod by means of the at least one spherical joint.
 11. Thedevice for the quantitative analysis of debris preferably produced whiledrilling according to claim 1, wherein the at least one collection trayis provided with two lateral fins capable of preventing the lateralleakage of the debris.
 12. The device for the quantitative analysis ofdebris preferably produced while drilling according to claim 1, whereinthe at least one collection tray is provided with rear discharge portswhich allow the seeping of the more liquid part of the drilling slurry,so as to retain the solid fraction of said slurry inside said tray. 13.The device for the quantitative analysis of debris preferably producedwhile drilling according to claim 1, wherein the device comprisesnozzles for the washing of the at least one collection tray.
 14. Thedevice for the quantitative analysis of debris preferably produced whiledrilling according to claim 13, wherein said nozzles for the washing ofthe at least one collection tray are placed on a horizontal pipe with alength equal to that of said tray, said pipe being attached by means ofa system having an adjustable slant.
 15. The device for the quantitativeanalysis of debris preferably produced while drilling, according toclaim 1, wherein the device can operate both in manual and automaticmode.
 16. The device for the quantitative analysis of debris preferablyproduced while drilling, according to claim 15, wherein said automaticmode precedes the setting of work parameters via a workstation in aremote position.
 17. The device for the quantitative analysis of debrispreferably produced while drilling according to claim 3, wherein eachone of said four sensing elements generates an output electronic signalwith an electronic circuit part for the acquisition and processing ofsaid output signals.